Charge forming device



Dec. 5, 1933. F. E. ASELTINE ET AL CHARGE FORMING DEVICE Filed June 27', 1928 4 Sheet's-Sheet 1 5, 1933. F. E: ASEIJINE El AL CHARGE FORMING DEVICE Filed June 27, 1928 4 Sheets-Sheet 2 D3. 5, 1933. F. E. ASELTINE Er AL' I 1 1,937,933

CHARGE FORMING DEVICE Dec. 5, 1933. F. E. ASELTINE ET AL CHARGE FORMING DEVICE 4 Sheets-Sheet 4 Filed June 2'7, 1928 Patented Dec. 5, 1933 CHARGE FORMING DEVICE Fred E. Aseltine, Carl B. Kindl, and Wilford H.

Teeter, Dayton, Ohio, assignors, by mesne assignments, to Delco Products Corporation, Dayton, Ohio, a corporation of Delaware Application June 27, 1928. Serial N0. 288,683 55 Claims. (Cl. 123-119) This invention relates to charge forming devices for multicylinder internal combustion engines and more particularly to the type of charge forming device or carburetor comprising a plurality of primary fuel mixing chambers or primary carburetors, one for each intake port of the engine and cooperating respectively with a plurality of secondary fuel mixing chambers or secondary carburetors each located adjacent an engine intake port and receiving fuel air mixture from a pipe connected with one of the primary carburetors and receiving air when required through one branch of an air manifold which supplies air to all of the secondary carburetors, the quantity of fluid flowing through the secondary carburetors being controlled primarily by a single main air throttle which controls all of the said secondary carburetors. The primary carburetors receive their liquid fuel through a single fuel duct leading to a common float bowl.

Examples of carburetors of this type are shown in the applications of W. H. Teeter Serial No. 221,372, filed September 22, 1927; W. H. Teeter and Fred E. Aseltine Serial No. 221,371, filed September 22, 1927.

In the devices disclosed in the above applications a plurality of primary carburetors are provided one for each intake port. The fuel mixture from such primary carburetors is conveyed through small pipes to the secondary carburetors adjacent each engine intake port where it is mixed with secondary air admitted through a port controlled by a spring held valve. In these devices throttling of the engine is effected by a single primary throttle which controls all the primary carburetors and a single main throttle controlling flow of air through the main air manifold. These throttles are operated from a common operating mechanism which is so arranged that the primary throttle controls the quantity of mixture passing to the engine up to a certain engine speed, for example that corresponding to a vehicular speed of 20-25 miles per hour, after which the main air throttle begins to open and becomes the main controlling element regulating the mixture outflow.

The general objects of the devices disclosed in the applications above mentioned are to provide a fuel mixture having proper proportions of fuel and air under all operating conditions, and to secure equal distribution of this mixture to the various engine cylinders without the application of heat either to the liquid fuel before mixture thereof with air, or to the fuel air mixture.

Various means for controlling the proportions of fuel and air in the mixture and devices for securing equal distribution of this mixture are disclosed in the applications above enumerated.

It is the principal object of this invention to provide novel and improved devices for controlling the proportions of fuel and air in the mixture, and improved means for securing equal distribution and delivery of the proper quantity of fuel mixture to the various engine intake ports.

With this object in view one feature of the invention consists in the provision of a plurality of primary carburetors, one associated with each engine intake port, a throttle controlling said carburetors and means for admitting air to said primary carburetors in advance of the fuel inlets to control the effect of dynamic suction or velocity head on said inlets, said air admitting means being controlled by the primary throttle.

A further feature of the invention consists in the provision of a suction operated secondary air valve for controlling the flow of secondary air, said valve being positioned in the main air passage which admits air to the air manifold so as to be subject to manifold suction at all times. Another feature of the invention comprises means for controlling the opening movement of the suction operated secondary air valve, so constructed as to normally retard the opening of said valve, but operating to permit said valve to open freely on opening of the throttle at high engine speed.

Another feature of the invention lies in the provision of a resilient operating connection between the main air throttle and the suction operated air valve, by means of which the throttle when operated tends to operate the said air valve.

A still further feature of the invention consists in the provision of an improved form of fuel pump operated by the main air intake valve for providing fuel to enrich the mixture for acceleration, said pump operating to inject a quantity of fuel into each primary mixture passage whenever the pump is operated.

An additional feature of the invention consists in the provision of a dash pot or other means for retarding the opening movement of the suction operated secondary air valve, hav- 105 ing means for controlling its retarding effect during the entire opening movement of the valve and means for reducing its retarding eifect which is efiective during a part of the opening movement of said valve. More specifically, this 9 feature of the invention consists of a by-pass, normally closed but opened during opening movement of the valve, for permitting the passage of fuel around the dash pot piston, and another bypass allowing escape of fuel from the dash pot cylinder during the entire opening movement of the air valve and provided with a valve for regulating the area of the by-pass.

A further feature of the invention consists in the provision of a fuel conduit extending from the fuel pump to the primary carburetors which is provided with a vent passage for admitting air at atmospheric pressures to prevent the high suction maintained in the primary carburetors operating to lift fuel from the pump through such passage to the primary carburetors.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a plan view of the present invention attached to the engine cylinder head, a part of which is shown in section.

Fig. 2 is a side elevation looking toward the engine block.

Fig. 3 is a section on line 33 of Fig. 1.

Fig. 4 is a section on line 44 of Fig. 1.

Fig. 5 is a fragmentary detail section on the line 5-5 of Fig. 3.

Fig. 6 is a detail view of the primary throttle valve.

Fig. '7 is a fragmentary section on line 7-7 of Fig. 4.

Fig. 8 is a fragmentary section on the line 88 of Fig. 3.

Fig. 9 is a side elevation of the main carburetor unit looking from the right in Fig. 2.

Fig. 10 is a side elevation of the main carburetor unit looking from the left in Fig. 2.

Fig. 11 is a detail section on the line 1111 of Fig. 9.

Fig. 12 is a fragmentary section on the line 12-12 of Fig. 10.

Fig. 13 is a detail section Fig. 10.

Fig. 14 is a plan view of the casting in which the dash pot cylinders are formed.

Fig. 15 is a detail elevation of the lever 116 and cooperating mechanism viewed from the left in Fig. 10.

Fig. 16 is a horizontal section on line 16-16 of Fig. 3.

Fig. 17 is a section through the secondary mixing chamber on line 17-17 of Fig. 2.

Figs. 18 and 19 are detail sections at right angles to each other of the float valve mechanism and fuel inlet passage controlled thereby.

Fig. 20 is a detail section on the line 20-20 of Fig. 3.

Fig. 21 is an end elevation of the block 157 with the fuel and air passages therein shown in dotted lines.

It will be observed that the main air passage which admits air to the secondary mixing chambers has in some instances in this specification been termed a secondary air passage, while the air flowing through such passage has been termed "secondary air. These terms have been used to distinguish from the primary air passage and primary air which goes to the primary mixing chambers.

on line 1313 of The device disclosed herein comprises a main air manifold indicated in its entirety by the reference character 10, and having three outlet branches 11, 12, and 13 each of which is adapted to communicate with one of the ports 14 of a multi-cylinder engine. Each port serves two adjacent cylinders through valve ports 14a and 14b, as clearly indicated in Fig. 1. The cylinder head is shown in three separate fragments 15, but it will be understood that it may be an integral structure. The branches ll, 12 and 13 are each provided with an attaching flange 16, for attaching the manifold to the engine block in the conventional manner. Adjacent the inlet of the manifold is provided a flange 17 to which may be'secured the main carburetor unit as shown in Fig. 3.

The main carburetor unit comprises a main housing in the form of a single casting 18, at tached by screws 19 to the flange 17. An air inlet horn 20, the flow of air through which is regulated in a manner later described, is secured in position over an opening in the upper wall of said housing by screws 22 which pass through flanges 23 and 24 on the horn and housing respectively. A casting 25 having certain dash pot chambers and fuel passages, described in detail hereinafter, formed therein is secured by screws 26 to the lower wall of the main housing 18, a gasket being provided between the castings 105,

to make a tight joint, and a sheet metal fuel bowl 27 is held tight against a shoulder 28 on said main housing 18 by means of a screw 29 which is screwed into a post 30 depending from and integral with the casting 25.

A fuel line leading to a main source of fuel supply (not shown) is connected to a nipple 31, screwed into the main housing 18 as shown in Fig. 1. This nipple may have a screen secured therein in a manner well known so that incom- 11E ing fuel must pass through the screen and said nipple communicates with a bore 32 formed in the wall of housing 18, the bore 32 connecting with bore 33 also in the wall of said housing as shown in Fig. 19. At its inner end the bore 33 connects with a vertical bore 34, which in turn communicates with a bore 35 in casting 25. A plug 36 is screwed into the lower end of bore 35 and is provided with lateral fuel outlets 3'7 through which the fuel flows into the float chamber. Cooperating with valve seat 38 is a valve 39 controlled by a float 40 pivoted at 41. The valve operates in the usual manner to maintain a constant fuel level in the said float chamber. 139

Fuel is conducted from the fuel bowl to a plurality of primary fuel nozzles 42 located in the primary mixing chambers 43 formed in the central part of the main housing which may be termed the distributor block. The construction of the distributor block and cooperating elements comprising the primary carburetors will be more fully described hereinafter. To permit the fuel to flow from the fuel bowl to the primary nozzles 42 the casting 25 is provided with a vertical 14c fuel conduit 44 which communicates at its upper end with a horizontal fuel canal 45 which connects with each of the nozzles 42 through holes 46. Fuel is admitted from the fuel bowl to the conduit 44 at low speed through a metering orifice 47. All of the fuel flowing to the fuel nozzles 42 up to a certain predetermined engine speed, for example that corresponding to a vehicular speed of approximately 20 miles per hour, passes through the metering orifice 47.

For higherspeeds than said predetermined speed fuel is also admitted to the fuel conduit 44 through an orifice 48 co'ntrolled by a fuel valve 49, operated in a manner fully described hereinafter, and thence through ,a horizontal channel 50, connecting with the lower end of conduit 44.

Fuel is lifted from the fuel bowl through the nozzles 42 to the primary mixing chambers by the suction therein. When the throttle is moved toward closed position to reduce the engine speed there is a sudden reduction in suction on the vertical column of fuel between the fuel bowf and the nozzle which might permit this column of fuel to drop sufllciently to cause a temporary starving of the engine unless means were provided to prevent the dropping of such column of fuel. To prevent this action a check valve 51 is received in an enlarged chamber 52 at the junction of channels 44 and 45 and on reduction of suction in the primary mixing chambers rests on an annular seat projecting upwardly from the bottom of such chamber around the upper end of conduit 44 preventing downward flow through said conduit.

The metering orifice 47 is drilled in the casting 25 and the drill hole on the opposite side of the conduit 44 is plugged by a screw 53.

Each primary fuel nozzle is shown herein as provided with a main fuel outlet in the top of the nozzle and a secondary fuel outlet comprising two holes 54 and 55 formed in the vertical wall of the nozzle near the bottom of the mixing chamber 43 and diametrically opposite each other as shown in Fig. 3. At higher speeds there is suflicient suction in the primary mixing chambers to cause fuel to flow from the main fuel outlet in the top of each primary nozzle, as well as from the holes 54 and 55. At idle or very low speed, however, there is insufficient suction to cause such a flow of fuel, the fuel at such time standing in the nozzle at a point between the top of the nozzle and the orifices 54 and 55, flowing from such orifices by action of gravity. Each fuel nozzle is provided with a restricted fuel metering orifice 56.

In the carburetor disclosed herein the central portion of the main casting constitutes the distributor block and is indicated at 60 in Fig. 3. The distributor block has three primary mixture passages 61, 62, and 63 formed therein, such passages being parallel to each other and close together as indicated in Fig. 16. All of these passages extend straight through the block and when the device is assembled are in register with three passages 61a, 62a and 68a formed in the manifold wall. The passage 62a extends straight through the wall of the manifold, but passages 61a and 63a are L-shaped as indicated in Fig. 16. Each of these passages has associated therewith a pipe for conveying the primary mixture to the secondary mixing chambers as fully described hereinafter. The inlet ends of the primary mixture passages where the nozzles project into such passages are of larger diameter than the outlet ends thereof and between the inlet and outlet end of each passage its cross which register therewith. This throttle valve has spindles 67 projecting from each end on which certain operating connections are secured and is rotatably mounted in the walls of housing 18. A groove 68 is provided in the throttle which cooperates with the inner end of a screw 69, adjustable in the casting, to prevent longitudinal movement of the said throttle. The passage 62a has a tube 70 secured therein in any desirable manner while the passages 61a and 63a communicate with pipes 71 and 72 respectively. These pipes are connected at one end to the outlets of passages 61a and 63a while the other ends of such pipes connect with elbows 74 detachably secured to the manifold branches 11 and 13, the outlet ends of such elbows being in alignment with tubes 75 and 76, similar to the tube 70, and which are secured in manifold branches 11 and 13 respectively in any suitable manner. Primary mixture is drawn by engine suction from the primary mixing chambers through the pipe connections above described, and tubes 70 and 75 and 76 to the secondary mixing chambers in which such tubes terminate. The primary mixture may be mixed with additional air in the secondary mixing chambers in a manner more fully described later.

Substantially all the air entering the car-' buretor flows through the air horn 20, the flow therethrough being controlled by a main air valve 77, normally held against a seat 78 by a spring 79. Air flows past the valve 77 to a main air chamber 80 formed in the housing 18. An air conduit 81 controlled by a valve mechanism hereinafter described connects the air chamber with the main air manifold while an orifice 82 in the floor of the air chamber per- 'mits a flow of air from the chamber 80 to the primary carburetors.

When the carburetor is choked to start the engine the air valve 77 is held against its seat by means presently described to completely close the main air inlet. To provide sufficient air to carry the starting fuel from the primary nozzles to the engine when the carburetor is choked as described, an air inlet 83 is provided. This inlet is an elongated slot formed in a plate 84 secured to the housing 18 as shown in Fig. 3.

Owin to the size of the air inlet orifice 82 relative to the total area of the constrictions 64 in the primary mixture passages the suction effective at each fuel nozzle would be substantially the static suction of the air valve chamber at very low speeds or idling even if no other means were provided to prevent the formation of a velocity head at the nozzles. At all other speeds, however, the air velocity past the nozzles would be sufficient to build up a velocity head at the nozzles. Moreover, as the throttle opens to increase the engine speed, the air velocity at the nozzles and the resulting velocity head would increase so rapidly that the increase in fuel flow would be such as to form a mixture too rich for proper engine operation. Means are provided which cause the velocity head at the nozzles to increase gradually during opening movements of the primary throttle until a certain predetermined engine speed is reached and to compensate for this, gradual rise in the velocity head the fuel jets are calibrated somewhat smaller than would be theoretically correct, so that at speeds lower than the predetermined speed the fuel flow is such as to form a mixture of proper proportions. This predetermined engine speed is that corresponding to a vehicular speed of 20-25 miles per hour for example.

The above mentioned means comprises three air channels 85 connecting the air chamber with the primary mixture passages at a point just posterior to the constriction 64 therein. These channels are identical and admit air to the primary mixture passages immediately posterior to the nozzles. The admission of air at this point prevents a very great increase in air velocity past the nozzles as the primary throttle is opened until said throttle reaches the predetermined position referred to, because a part of the increased supply of air flows through passages 85. After the predetermined engine speed above referred to has been reached the suction in the primary mixture passages becomes so great that the admission of air;

through passages is ineffective to prevent too rapid increase in air velocity past the nozzle and consequent increase in velocity head; and other devices, described in detail hereinafter, are provided to prevent too rapid increase in velocity head when the throttle 65 is opened beyond the predetermined position above referred to.

During operation at all engine speeds below the predetermined speed above referred tothe mixture formed in the primary carburetors is of properly combustible proportions and such mixture is conveyed to the engine without dilution by admixture with additional air in the secondary carburetors. At higher engine speeds the velocity head present at the nozzles causes so rapid a flow of fuel that the primary fuel mixture becomes super-rich in fuel c ntent, also the capacity of the primary mixture tubes is insufficient to supply a great enough quantity of fuel mixture to meet the engine demands at higher speeds. To offset the increase in fuel flow and to supply a sufficient quantity of fuel mixture at such speeds the air passage 81 leading from chamber 80 to the main air manifold is opened, in a manner hereinafter described to admit air to the secondary mixing chambers to dilute the primary mixture therein. This admission of air through the main air passage also acts to prevent any increase in the velocity head at the nozzles at speeds above the predetermined speed previously referred to, in fact, as set forth more fully later, the velocity head is reduced and eventually substantially disappears.

The increase in fuel flow caused by the presence of a velocity head at the nozzles is utilized as a means to effect enrichment of the mixture on wide open throttle to produce maximum power. Forthis reason the air inlet channels 85 are so bored in the wall of the distributor block that the delivery ends of such channels terminate in the bore in which the throttle 65 rotates. The grooves in this throttle are so constructed that when the throttle is nearly closed and throughout its movement for low speed operation the channels 85are wide open, but as the throttle is opened to secure higher engine speed the channels 85 are gradually closed, until at fully open throttle said channels are closed completely. This will cause a greatly increased velocity of air movement past the fuel nozzles when throttle 65 is fully open, building up a velocity head at such nozzles that will produce a rich mixture for maximum power.

The main air valve 7'7 is adjustably secured on a stem 86 slidably mounted in a guide sleeve 87 fixed in the main housing 18. Surrounding the guide sleeve 87 is a slidable sleeve 88, the lower end of which has a projecting disk 89 secured thereto the disk prov ding a seat for the air valve spring '19. Means are provided for raising this sleeve to a position where the upper end thereof will engage the air valve to hold it against its seat to choke the carburetor. This means comprises an arm 90 secured to a rock shaft 91 rotatably mounted in the wall of the main housing 18. The arm at its inner end has two pins 92 and 93 secured therein between which the disk 90 is received. The shaft 91 projects through the wall of the casing and at its outer end is bent to form an arm 200 having a hole 201 therein in which some form of operating connection. extending from a point convenient to the operator may be attached. An adjustable stcp screw 202 is received in a lug detachably secured to the air horn as indicated in Fig. 2. By adjustment of the stop screw the normal position of the sleeve 88 may be determined to regulate the tension of spring '79. Ordinarily the stop screw is so adjusted that the main air valve will open slightly during idling.

Flow of air from the chamber 80 to the secondary carburetors is controlled by two valves, a manually operated butterfly throttle 94, and a suction operated valve 95. The valve 94 is fixed on a shaft 96 which is journalled for rotation in the walls of the housing 18, and is operated simultaneously with throttle 65 through connections hereinafter described. The valve is fixed to a shaft 97 which is positioned off center with respect to the valve, a greater portion of the valve being below the shaft than above. shaft 9'7 is supported for rotation in the walls of the housing 18 and is operated primarily by the engine suction, its operation being controlled by devices described later.

The operating connections for the throttle valves will now be described. Fixed on the end of one' of the throttle spindles 67 outside the housing 18 is an operating arm 98 having a hole in its free end to be connected to some suitable form of operating connection extending to a point convenient to the operator of the vehicle.

This operating arm 98 is connected through a 1 lost motion connection to an arm 99 secured by a split clamp to the end of shaft 94 outside the casing. An operating link 100 is pivotally connected to the arm 98, and a pin 101 projecting from the free end of arm '99 projects through a slot 102 in the link 100. A regulating screw 103 is threaded in lugs 104 projecting from the operating link and may be adjusted to regulate the length of the slot 102, the upper end of the said screw constituting the lower end of said slot. A tension spring 105 is connected at one end to the upper end of the link 100 and at its other end to the pin 101. The spring tends to hold the pin 101 against the upper end of slot 102. With both throttles closed the parts are in the position shown in Fig. 9, with the pin 101 in engagement with screw 103. As the operating arm 98 is rotated in a counter clockwise direction to open the primary throttle valve 65 the link 100 moves downwardly to a position where the upper end of slot 102 strikes pin 101 before the operating arm 99 of the air throttle 94 is moved so that the primary throttle is partly opened before the air throttle begins to open. The screw The' On opening movement of either throttle valve I the suction below the air valve 77 is increased and the air valve is opened against the tension of its spring permitting an inrush of air to the secondary mixing chambers which will be sufficient to lean the mixture unless means are provided to retard the opening movement of said valve. By retarding the opening of the valve the leaning of the mixture as well as fluttering of the air valve may be prevented. It will be understood, of course, that opening of the -air valve may be sufliciently retarded on opening of the throttle to enrich the mixture for acceleration, but in this particular embodiment of the invention opening of the air valve is not retarded to that extent.

To retard the opening movement of the air valve the lower end of the valve stem 86 has secured thereto a piston 106 which slides in a cylinder 107 formed in the casting 25. To secure the piston to the stem 86 a flanged member 108 is secured to the end of the stem and the piston is held in engagement with the flange thereof by a nut 109 screwed on the member 108. The lower end of the cylinder is closed by a closure member 110, having an opening 111 in the center thereof closed by an upwardly opening check valve which permits unretarded upward movement of the piston but prevents escape of fuel on downward movement of said piston, fuel'escaping on such downward movement only by leakage around the piston or through a pump delivery passage, later described, thus retarding opening movement of the valve.

In the wall of the dash pot cylinder is formed a by-pass 113 both ends of which connect with the interior of the cylinder. The piston 106 stands opposite the upper end of the by-pass when the air valve is closed, preventing flow through the by-pass when in such position. As the piston descends the upper end of the by-pass is gradually uncovered allowing fuel to pass from the space within the cylinder below the piston.

As set forth in detail hereinafter the above described dash pot operates as a pump to provide additional fuel to enrich the mixture for acceleration under certain operating conditions and the principal purpose of the by-pass above described is to render the dash pot inoperative as a pump after a certain movement of the piston 106 for reasons later set forth. Of course, the by-pass operates as a means to vary the resistance to motion of the piston 106 also and consequently varies the retarding effect on oneing movement of the air valve to some extent.

When the main throttle valve 94 is opened the suction in the chamber below the air valve 77 is so greatly increased that although the suction at the nozzles is increased and at the same time the opening movement of the main air valve is retarded to some extent to prevent leaning of the mixture the additional air flow into the secondary mixing chambers through the main air passage, past the throttle valve 94 would be so rapid as to prevent any enrichment of the mixture immediately, and such enrichment is necessary to provide sufficient fuel for proper engine acceleration. To provide additional fuel to enrich the mixture a pump, hereinafter fully described, is provided and the automatic air valve in'themain air passage is retarded in its opening movement to assist the action of the pump.

The air valve 95 is retarded during its opening movements primarily for the purpose of producing at all times, when the throttle 94 is opened, a suflicient pressure differential between the inlet and outlet ends of the primary mixing tubes to create a velocity of flow through such tubes great enough to transport the primary mixture from the primary mixing chambers to the secondary mixing chambers substantially instantaneously. In the device disclosed herein the aforementioned pump forces fuel for acceleration into the primary mixing tubes to form a super-rich mixture therein. If the air valve 95 were allowed to open freely the pressure differential between the two ends of the primary tubes would be too 'low to create a very high air velocity therein and a perceptible interval of time would be required to carry this super-rich mixture to the secondary mixing chambers. The secondary air entering through the main air passage would reach the secondary chambers before the super-rich mixture and would weaken the mixture therein instead of, enriching it. By retarding the opening movement of valve 95 this difficulty is avoided. The suction at the outlet ends of the primary tubes is maintained high enough to produce so high a velocity of air flow through the primary tubes that the super-rich mixture reaches the secondary mixing chambers substantially simultaneously with the opening of the throttle. Of course, the retarding of the opening movement of air valve 95 also retards the flow of air through the main air passage to some extent during the accelerating period, increasing the time necessary for the secondary air to reach the secondary mixing chambers making this period substantially the same as that required for the primary mixture to reach such chambers. Y

To control the movement of the valve 95, its operating shaft is provided on one of its ends which projects outside the main housing 18 with a forked arm 114 secured to the shaft by a split clamp. The forked end of said arm engages a pin 115 on one arm of a bell crank lever 116, pivoted on the housing wall at 117. The horizontal arm of the bell crank is pivotally connected by a pin 118 with a coupling memher 119 adjustably secured to the upper end of a piston rod 120 which has mounted on its lower end a dash pot piston 121 received in a cylinder 122 formed in the casting 25. The cylinder is open at its upper end and is closed at its lower end by a closure plate 123. The piston is slidably mounted on a sleeve 124 secured to the rod by pin 125 and is normally held against an upstanding annular rim 126 formed on a flange 127, projecting from the sleeve 124 by a spring 128 received around the sleeve between the up per face of the piston and a nut 129 adjustable on the sleeve to regulate the spring tension. The piston is provided with holes 130 which permit a flow of fuel through the piston when the piston is lifted from the annular seat 126 for a purpose more freely set forth hereinafter.

An orifice 131 is formed in the bottom of the sleeve 124 and another orifice 132 in the side 5 thereof to permit a flow of fuel therethrough and allow unretarded upward movement of the piston, the flow of fuel through these orifices being prevented on downward movement of the piston by a disk check valve 133 mounted on pins 134 projecting from the flange 127 and having limited movement'between the flange and enlarged heads on the pins 134. A spring 135 fixed on one of the pins 133 normally holds the check valve in its upper position.

A by-pass 136 similar in construction to the by-pass 113 previously described is formed in the wall of the dash pot cylinder 122. The up-' per end of this by-pass is closed by the piston when in its upper position with valve closed. The purpose of this by-pass is to vary the resistance to downward motion of the dash pot piston. to vary accordingly the retarding effect on opening movement of the air valve. As the by-pass is being uncovered by the piston the retarding of the valve movement is reduced, allowing the valve to open more rapidly as it approaches open position to supply sumcient air to the engine to give the required power as the fuel flow and engine speed increase. The relation of the by-pass to the piston determines the duration of the valve damping and this relation is varied automatically according to the position of the throttle valve. The greater the initial opening of the throttle valve at the time it is suddenly opened further to accelerate, the less will be the damping action. This variation is desirable because less damping of the valve would be required when the throttle is moved from a 20 to 30 miles per hour throttle position than from 10 to 30 miles per hour position, assuming that operating conditions are otherwise the same.

In addition to the by-pass above described there is provided a fuel passage 137, connecting the interior of the dash pot cylinder below the piston and the fuel bowl to permit escape of fuel from the said cylinder as the piston descends. The size of this passage may be regulated by a needle valve 138 having a knurled head 139, held in adjusted position by a spring detent 140. Adjustment of the valve to regulate the size of passage 137 will vary the resistance to movement of the dash pot piston.

Under certain operating conditions, when the suction effective on the air valve is very suddenly and very greatly increased the piston 121 is moved downwardly so rapidly that the resistance to its motion is great enough to overcome the pressure of spring 128 and lift the piston from the seat 126 permitting fuel to flow from below the piston through the holes therein and allow the valve 95 to open freely. Once lifted from the seat 126 the piston will remain off the seat until the downward movement of the valve ceases. As an example of operating conditions when the piston will be lifted from the seat as described it may be assumed that the vehicle is coasting down hill at a speed of 35 to 40 miles per hour with the throttle 94 closed and clutch engaged. If an up grade is reached and the throttle is opened it is not desirable to retard the opening of the air valve because the engine is already running at speed and no mixture enrichment is necessary but suilicient air must be admitted to provide the necessary volume of charge to give the necessary power.

While the valve 95 is moved principally by engine suction, movement of the throttle 94 tends to move such valve through the medium of resilient operating connections which will now be described. On one end of the shaft 96 is secured by means of a split clamp an arm 141,

At its free end this arm is bored and received in said bore is a rod 142 connected at its lower end to the arm of bell crank 116 which is connected to piston rod 120. Surrounding the rod above and below the point of connection with arm 141 are springs 143 and 144 respectively. These springs are mounted on the rod between two collars 145 and 146 slidable on the rod and engaging the end of am 141, and two collars 144 and 148 adjustably secured on the rod by set screws as indicated in Fig. 10. It will be clear that movement of the arm 141 either upwardly or downwardly will compress one or the other of springs 143, 144, tending to move rod 142 either up or down. The primary purpose of the above described mechanism is to open the valve 95 to its full open position under certain operating conditions when the manifold suction at wide open throttle is insufllcient to more than partially open the valve 95. For 9- instance, when the engine is operating slowly at wide open throttle and under heavy load, as when the vehicle is ascending a steep hill, the manifold suction is so low that the valve 95 would not be fully opened and the volumetric 10 efllciency correspondingly reduced. Movement of throttle 94 to wide open position will compress the spring 144, however, sufficiently to fully open the valve 95.

In addition to the above described devices 10! for enriching the mixture a means is provided for supplying additional fuel at all engine speeds above that at which the air valve 95 begins to open. This additional fuel supply means is made necessary by the rapid reduction and final 11f.

substantial elimination of the velocity head at the fuel jets caused by opening the air valve 95. Since fuel metering means is calibrated to compensate for a velocity' head which is present at said jets during engine operation throughout the lower speed ranges, the jets do not supply sufficient fuel to form a rich enough mixture for proper engine operation after the valve 95 is opened unless some fuel supply means in addition to the above mentioned metering device is 11! provided.

This fuel supply means comprises the valve 49, previously referred to, which is operated by an arm 149 pivoted at 150 on the outside of the housing 18, as shown inFig. 10. Projecting from the opposite end of arm 149 is a pin 151- which is received in a bore in an enlarged head 152 into which the valve 49 is screwed. A cam 153 is fixed on the spindle 67 projecting from the opposite end of the throttle 65 to that on which its operating arm 98 is secured and cooperating with this cam is a roller 154 mounted for rotation on a pin projecting from the arm 149. A considerable portion of the cam is concentric relative to its operating shaft so that it is inefl'ective to raise arm 149 to open the fuel valve until a certain predetermined speed is reached, for example an engine speed corresponding to a vehicular speed of approximately 20 miles per hour. By using a cam of different g shape the time of opening the fuel valve may be regulated as desired. Also by adjusting the valve in its head 152 the normal position of the valve prior to its opening movement by arm 149 may be determined.

Another mixture enriching device is provided in addition to the various devices heretofore described in detail for controlling the proportions of air and fuel in the mixture under various different operating conditions. This de- 150 vice comprises the pump above alluded to for pumping a charge of fuel into the primary mixto accelerate at any time that the air valve piston is not below the upper end of by-pass 113. The air valve dash pot comprising piston 106 and cylinder 10'! constitutes the pump and operates whenever the piston moves downwardly on opening movement of the air valve. A fuel delivery conduit 155 is received at its lower end in a hole in the cylinder 107 near the bottom thereof while the upper outlet end of said conduit connects with a fuel channel 156 in a block 157 secured in any desirable manner to the bottom of the distributor block, in a position somewhat posterior to the throttle valve as indicated in Fig. 3. The block 157 extends across all of the primary mixture passages and fuel passages 158, 159 and 160 formed in the block communicate with passages 161, 162 and 163 drilled in the bottom wall of the distributor block, and communicating with the primary mixture passages 61, 62 and 63 respectively, as shown in Figs. 3 and 20. Two air channels 164 admit air to the fuel channel 156, the entering air forming an emulsion with the fuel which issues from passages 161, 162 and 163 into the primary mixing passages.

The reason for admission of air to the fuel channel 156 is to prevent the high suction maintained in the primary carburetors acting to draw fuel from the dash pot cylinder independently of the pumping action of the piston 106. It will be understood that under all conditions of operation a very considerable degree of suction is maintained in the primary mixing chambers and unless the fuel delivery passage between the dash pot cylinder andthe primary mixture passages be vented to atmosphere at some point therein, this high suction would operate to lift fuel from the dash pot cylinder at all times, whereas it is desirable to deliver fuel from the dash pot cylinder to the primary mixture passages only when the throttle is opened to cause downward motion of the piston 106. By admitting air to the fuel channel 156 the suction effective to lift fuel through conduit 155 is never great enough to lift the fuel to the channel 156, but is sufficient only to lift fuel in conduit 155 to some point intermediate the dash pot cylinder and the fuel channel 156, preferably to a point immediately below this channel.

When the throttle'is opened to increase the speed the resulting increase in suction in air chamber forces the air valve 77 and piston 106 downwardly, forcing fuel upwardly through conduit 155 and the outlets therefrom to the primary mixture passages, air being mixed with the fuel in channel 156 in the manner heretofore described. This pumping action continues as long as the piston 106 is in position to close the upper end of the by-pass 113. As soon as the piston moves to position to open the by-pass the pumping action described ceases and further downward movement of the piston operates merely to force fuel from the lower part of the cylinder through the by pass to the upper portion of aid cylinder.

It will be noted that the pump operates to force fuel for acceleration purposes into the primary mixture passages in this device, rather .than into the main air stream as in the applications previously referred to. In the devices disclosed in the above mentioned applications the flow of air through the secondary air passage is not momentarily retarded subsequent to the opening of the secondary air valve. Consequently the air flowing through the secondary air passage reaches the secondary mixing chambers substantially immediately on opening or the said air valve. It is, therefore, desirable in such devices to inject fuel directly into said secondary air stream, for if the additional fuel were pumped into the primary mixture passages, the pure air flowing through the secondary air passage would reach the secondary mixing chambers before the enriched primary mixture, resulting in a temporaryv weakening of the mixture. m the device disclosed herein, however, the delayed opening of the valve results in the rich primary mixture reaching the secondary mixing chambers substantially simultaneously with the air passing through the secondary air passage; It is, therefore, unnecessary in this device to inject the pumped fuel into the air flowing through passage 81, but such fuel can be injected into the primary mixture passage and will reach the secondary mixing chambers so nearly simultaneously with the opening of the throttle that proper enrichment of the mixture is secured immediately.-

The injection of the fuel for mixture enrichment into the primary mixture passages is a decided improvement over the earlier form of device because better distribution of such fuel is secured. Substantially equal pressure is maintained in all of the primary mixture passages so that substantially equal amounts of fuel are pumped into each primary tube to be conveyed to each secondary mixing chamber. This will give better distribution than would be possible if the whole charge of fuel were pumped into the single main air intake passage for distribution to the various secondary mixing chambers, in which the pressure at any given instant is never the same. If the fuel be injected into the main air stream the secondary mixing chamber in which the greatest suction was present at the time of injection of the fuel would necessarily receive the greater part of such fuel.

The secondary mixing chambers comprise Venturi tubes 175 or other flow accelerating elements. There are three of these venturis 1'75 which are identical in construction and are positioned in the branches 11, 12 and 13 of the manifold 10, in such relation to the primary mixing tubes, that the point of greatest depression or suction in each Venturi tube is immediately adjacent the outlet end of the primary mixing tube 70 associated therewith. Each venturi is provided with an annular projecting rib 176 which fits, when the manifold is attached to the engine block, both in the engine intake port and in a recess 1'77 in the end of the associated branch of the manifold, the rib engaging a shoulder 178 when the venturi is in position. A channel 179 is formed in the outer wall of said venturi, at the bottom of the element when the device is assembled. to permit any fuel which precipitates out of the mixture and collects on the wall of the manifold branch to flow into the engine intake port. The venturis cause the main air currents to assume high velocity at the ends of tubes 70, '75, and 76, creating in each 15,:

tube a high suction when the throttles are open.

It will be understood that while the means for temporarily retarding the passage of air through the secondary air passage on opening of the throttle 95 is illustrated herein embodied in a charge forming device provided with a pump for supplying additional fuel to the primary mixture on opening of the throttle, the utility of said retarding means is not limited to such a charge forming device. While it is particularly desirable to retard the flow of air through the secondary air passage when the pump is provided to enrich the primary mixture on opening of the throttle, it should be clear that such retardation is desirable even when the primary mixture is not enriched. In such event the unretarded admission of pure air through the secondary air passage would also result in a temporary weakening of the mixture and unsatisfactory acceleration.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A charge forming device for internal combustion engines having in combination, amixing chamber, a fuel inlet therefor, a primary air inlet therefor, a secondary air passage, a throttle, a main air inlet admitting air to said primary air inlet and to the secondary air passage, a valve in said main air inlet, a dash pot for retarding the opening movement of said valve, a secondary air valve in said secondary air passage, a dash pot for retarding the opening movement of said secondary air valve, automatic means for varying the retarding effect of the dash pot associated with said secondary air valve, and manual means for varying the retarding effect of said dash pot.

2. A charge forming device for internal combustion engines having in combination a mixing chamber, a fuel inlet therefor, a primary air inlet therefor, a secondary air passage, a throttle, a main air inlet admitting air to said primary air inlet and to the secondary air passage, a valve in said main air inlet, a dash pot for retarding the opening movement of said valve,

a secondary air valve in said secondary air passage, a dash pot for retarding the opening movement of said secondary air valve, automatic means for varying the retarding effect of the dash pot associated with said secondary air valve, manual means for varying the retarding effect of said dash pot, and means for eliminating the retarding effect of said dash pot on rapid opening of the throttle to permit the secondary air valve to open freely.

'3. A charge forming device for internal combustion engines comprising a primary mixture passage, means for admitting fuel and air thereto, a throttle valve regulating the flow through said passage, a secondary mixing chamber into which said primary mixture passage delivers, a second air passage supplying air to said secondary mixing chamber, a throttle valve in said secondary air passage, an automatic suction operated valve in said secondary air passage, means for retarding the opening of said valve on opening movement of the secondary throttle and means for adjusting the retarding effect of said last named means.

4. In a charge forming device for a multi cylinder -engine having a plurality of intake ports, the combination of a main air manifold having branches leading to said intake ports and forming secondary mixing chambers, a plurality of primary carburetors for supplying fuel mixture to said secondary mixing chambers,

a single air intake passage supplying air to all of said secondary mixing chambers, a throttle for controlling the flow through said passage, a suction operated valve in said passage for modifying the effect of the throttle means for retarding the opening movement of the valve and means for adjusting the retarding effect of said last named means.

5. A charge forming device for internal combustion engines having in combination a secondary mixing chamber, a primary carburetor for supplying primary mixture to said secondary mixing chamber, an air passage for admitting air to said secondary mixing chamber, an air throttle in said air passage, an air valve in said passage, connections between said throttle and said air valve whereby the throttle when operated tends to operate said valve but permitting operation of said valve independently of the throttle.

6. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary carburetor for supplying primary mixture to said secondary mixing chamber, an air passage for admitting air to said secondary mixing chamber, an air throttle for controlling flow through said air passage, a

supplemental valve controlling flow through said passage and a resilient connection between the throttle and supplemental valve.

7. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary carburetor for supplying primary mixture to said secondary mixing chamber, an air passage for admitting air to said secondary mixing chamber, an air throttle for controlling flow through said air passage, a supplemental valve controlling flow through said passage, a primary throttle for controlling the flow from the primary carburetor, a positive operating connection between said primary throttle and the air throttle and a resilient connection between said air throttle and the supplemental valve.

8. A charge forming device for internal combustion engines comprising a primary mixture passage, fuel and air inlets for said primary mixture passage, a throttle, a secondary mixing chamber located between the throttle and the engine into which the primary mixture passage delivers a primary mixture of fuel and air, and means for injecting additional fuel into the primary mixture passage on opening movement of said throttle to enrich the mixture for acceleration. I

9. A charge forming device for internal combustion engines comprising a primary mixture passage, fuel and air inlets for said primary mixture passage, a throttle, a secondary mixing chamber located between the throttle and the engine into which the primary mixture passage delivers a primary mixture of fuel and air, means for injecting fuel into the primary mixture passage to enrich the mixture for acceleration, said means comprising a pump, a fuel delivery passage connecting the pump with the primary mixture passage, and means to admit air to said fuel delivery passage at some intermediate point between the pump and the primary mixture passage.

10. A charge forming device for an internal combustion engine comprising a secondary mixing chamber, a primary mixture passage delivering fuel mixture to said secondary mixing chamber, fuel and air inlets for said primary mixture passage, a throttle, a main air inlet, a valve for controlling said inlet, and a pump operated by said valve for injecting additional fuel into the primary mixture passage on opening movement of the throttle.

' 11. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality of primary carburetors for supplying fuel mixture thereto, means for admitting fuel. and air to said primary carburetors, and a single means for injecting additional fuel into all of said primary carburetors to enrich the mixture for acceleration.

12. A charge forming device for internal combustion engines having in combination a pmrality of secondary mixing chambers, a plurality of primary carburetors for supplying fuel mixture thereto, means for admitting fuel and air to said primary carburetors, means for-equalizing the pressure in said primary carburetors, means for injecting additional fuel into said primary mixing chambers to enrich the mixture for acceleration, said means including a single delivery passage leading to all of the primary carburetors whereby equal distribution of said additional fuel is secured.

13. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality of primary carburetors for supplying fuel mixture thereto, means for admitting fuel and air to said primary carburetors, means for equalizing the pressure in said primary carburetors, a pump for injecting additional fuel into the primary mixing chambers to enrich the mixture for acceleration, a fuel delivery conduit leading from the pump and a distributor element connected thereto, said element having a fuel channel formed therein and a plurality of passages, each of which communicates with said channel and with one of the primary mixing chambers.

14. A charge forming device for internal combustion engines having in combination a plurality of secondary mixing chambers, a plurality of primary carburetors for supplying fuel mixture thereto, means for admitting fuel and air to said primary carburetors, means for equalizing the pressure in said primary carburetors, a pump for injecting additional fuel into the primary mixing chambers to enrich the mixture for acceleration, a fuel delivery conduit leading from the pump, a distributor element connected thereto, said element having a fuel channel formed therein and a plurality of passages, each of which communicates with said channel and with one of the primary mixing chambers and means for admitting air to said channel.

15. A charge forming device for internal combustion engines having in combination a primary mixing chamber, fuel and air inlets therefor, a secondary mixing chamber, a conduit through which the primary mixture is conveyed to said secondary mixing chamber, an air passage admitting air to said secondary mixing chamber, a throttle, means for injecting additional fuel into said primary mixing chamber on opening movement of the throttle to enrich the mixture for acceleration, and means to simultaneously retard the flow of air through said secondary air passage to maintain a high vacuum and consequent high air velocity in the primary mixture conduit.

fuel. into the primary mixing chamber to enrich the mixture for acceleration, means to retard the flow of air through the secondary air passage to enrich. the mixture during opening movements of the throttle, and manually operable means for admitting additional fuel on opening movements of the throttle.

17. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a secondary air passage supplying air to said mixture passage, a secondary air valve in said air passage, a dash pot for retarding the opening movement of said secondary air valve, manual means for varying the effect of said dash pot, and automatic means for varying the effectof the dash pot.

18. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto; a throttle, a secondary air passage supplying air to said mixture passage, a secondary air valve in said air passage, means for retarding the opening movement of said valve, adjustable means effective throughout the movement of said valve for regulating the effect of said retarding means, and means rendered effective during the opening movement of the valve for reducing the retarding eifect of said retarding means.

19. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a

throttle, a secondary air passage supplying air 20. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a secondary air passage supplying air to said mixture passage, a secondary air valve in said air passage, a dash pot for retarding the opening movement of said secondary air valve, manual means for regulating the retarding effect of the dash pot, automatic means for reducing the retarding effect of the dash pot and additional automatic means for eliminating the retarding effect of said dash pot under certain operating conditions.

21. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a secondary air passage supplying air to said mixture passage, a secondary air valve in said air passage, a dash pot for retarding the opening movement of said secondary air valve, means for regulating the retarding eifect of the dash pot throughout the opening movement of the valve, means for reducing the retarding effect of said dash not during a part of the opening movement of the valve, and means for eliminating the retarding effect of said dash pot on any very rapid opening of said valve.

22. A charge forming device for internal combustion engines comprising a mixture passage,-

means for supplying fuel and air thereto, a throttle, a secondary air passage supplying air to said mixture passage, a secondary air valve in said air passage, a dash pot for retarding the opening movement of said secondary air valve, means for reducing the, retarding effect of said dash pot on opening of said air valve at higher engine speeds, and means for eliminating the retarding effect of said dash pot on very rapid opening of said air valve at any engine speed.

23. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air thereto, a throttle, a secondary air passage supplying air to said mixture passage, a secondary air valve in said air passage, a dash pot for retarding the opening movement of said secondary air valve, adjustable means for permitting escape of fuel from the dash pot cylinder to regulate the retar-ding effect of said dash pot, and additional means permitting escape of fuel-from said cylinder to reduce the retarding effect of said dash pot, said means being normally ineffective and rendered effective by the dash pot piston during secondary mixing chamber, fuel and air inlets for said primary mixture passage, a throttle controlling the flow therethrough, means for maintaining a relatively high velocity of flow through the primary mixture passage during operation under all operating conditions and a fuel pump operated on opening movements of the throttle for injecting additional fuel into the primary mixture passage to enrich the mixture during the acceleration period.

25. A charge forming device for internal combustion engines comprising a mixture passage, a fuel inlet therefor, an air inlet therefor, a supplemental air inlet supplying air to the mixture passage, a throttle for'regulating the mixture passage and for closing-the supplemental air inlet when the throttle is opened, a secondary air passage supplying air to the mixture passage and a suction operated valve in said secondary passage.

26. A charge forming device for internal combustion engines comprising a mixture passage, a fuel inlet therefor, an air inlet therefor, a supplemental air inlet supplying air to the mixture passage, a throttle for regulating the mixture passage and for progressively closing the supplemental air inlet as the throttle is moved toward open position, a secondary air passage supplying air to the mixture passage and a suction operated valve in said secondary passage adapted to be progressively opened as the throttle is opened.

27. A charge forming device for internal combustion engines comprising a mixture passage, a fuel inlet therefor, an air inlet therefor, a supplemental air inlet supplying air to the mixture passage, a throttle for regulating the mixture passage and for variably regulating the supplemental air inlet during substantially its entire opening movement, a secondary air passage supplying air to the mixture passage and a suction operated valve therein adapted to be opened only after the throttle has made a predetermined opening movement.

28. A charge forming device for internal combustion engines comprising a mixture passage,

a fuel inlet therefor, an air inlet therefor, a supplemental air inlet supplying air to the mixture passage, a throttle for regulating the mixture passage and for variably regulating the supplemental air inlet as the throttle is opened, a secondary air passage for supplying air to the mixture passage, 9. throttle operated valve there in, and means therein for temporarily retarding the flow of air therethrough as said valve is opened.

29. A charge forming device for internal combustion engines comprising a mixture passage, a fuel inlet therefor, an air inlet therefor, a supplemental air inlet'supplying air to the mixture passage, a throttle for regulating the mixture passage and for variably regulating the supplemental air inlet as the throttle is opened, a secondary air passage for supplying air to the mixture passage, a valve therein adapted to be opened after a predetermined movement of the throttle, and means therein for temporarily retarding the flow of air therethrough as said valve is opened.-

30.. A charge forming device for internal combustion engines having, in combination, a primary carburetor, fuel and air inlets therefor, a supplemental air inlet for the primary carburetor, a secondary mixing chamber adapted to receive a primary mixture of fuel and air from the primary carburetor, a secondary air passage supplying air to the secondary mixing chamber, valves controlling the supplemental air inlet and the secondary air passage, means for simultaneously closirig one of said valves as the other is opened, and a suction operated valve in said secondary air passage.

31. A charge forming device for internal combustion engines having, in combination, a primary carburetor, fuel and air inlets therefor, a supplemental air inlet for the primary carburetor, a secondary mixing chamber adapted to receive a primary mixture of fuel and air from the primary carburetor, a secondary air passage supplying air to the secondary mixing chamber, valves controlling the supplemental air inlet and the secondary air passage, means for simultaneously closing one of said valves as the other is opened, a suction operated valve in the secondary air passage, and means for retarding the opening movement of said suction operated valve on increase of engine suction to temporarily enrich the mixture during the acceleration period.

32. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets therefor, a throttle valve therein, a supplemental air inlet therefor adapted to be controlled by the throttle, a secondary air passage supplying air to the mixture passage, a valve therein operated by said throttle, and a suction operated valve in said passage.

33. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets therefor, a throttle valve therein, a supplemental air inlet therefor adapted to be controlled by the throttle throughout its operating range, a secondary air inlet passage supplying air to the mixture passage, a valve therein adapted to be opened only after a predetermined movement of the throttle and another valve in said secondary air passage operable only after the throttle operated valve has begun to open.

34. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets therefor, a throttle valve therein, a supplemental air inlet therefor adapted to be controlled by the throttle throughout its operating range, a secondary air inlet passage supplying air' to the mixture passage, a valve therein operated by said throttle and adapted to be opened only after a predetermined opening movement of the throttle and a suction operated valve in said passage operable only after said last named valve is opened.

35. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets therefor, a throttle valve therein, a supplemental air inlet therefor positioned adjacent the throttle so as to be controlled thereby, a secondary air passage supplying air to said mixture passage, a valve therein operated by the throttle, and a suction operated valve in said secondary air passage.

36. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets therefor, a throttle valve therein, a supplemental air inlet therefor positioned adjacent the throttle so as to be controlled thereby, a secondary air passage supplying air to said mixture passage, a valve therein operable by the throttle only after a predetermined movement of the latter, and a second valve in the secondary air passage operable only after said last named valve is opened.

37. A charge forming device for internal combustion engines comprising a primary mixing chamber, fuel and air inlets therefor, a secondary mixing chamber located adjacent the engine and relatively remote from the primary mixing chamber to which the latter is adapted to de liver a primary mixture of fuel and air, a primary throttle, a supplemental air inlet for the primary mixing chamber controlled by said throttle, a secondary air passage supplying air to the secondary mixing chamber, a manually operable valve therein, and a suction operated valve therein.

38. A charge forming device for internal combustion engines comprising a primary mixing chamber, fuel and air inlets therefor, a secondary mixing chamber located adjacent the engine and relatively remote from the primary mixing chamber to which the latter is adapted to de-.

liver a primary mixture of fuel and air, a primary throttle, a supplemental air inlet for the primary mixing chamber controlled by said throttle, a secondary air passage supplying air to the secondary mixing chamber, a manually operable valve therein, a suction operated valve therein and means for retarding the opening movement of the suction operated valve.

39. A charge forming device for internal combustion engines comprising a primary mixture chamber, fuel and air inlets-therefor, a secondary mixing chamber located adjacent the engine and relatively remote from the primary mixing chamber to which the latter is adapted to deliver a primary mixture of fuel and air, a primary throttle, a supplemental air inlet for the primary mixing chamber controlled by said throttle, a secondary air passage supplying air to the secondary mixing chamber, a valve in the secondary air passage operated by the primary throttle and a suction operated valve therein operable only after said last named valve has been opened.

4,0. A charge forming device for internal combustion engines comprising a primary mixing chamber, fuel and air inlets therefor, a secondary mixing chamber located adjacent the engine and relatively remote from the primary mixing chamber to which the latter is adapted to deliver a primary mixture of fuel and air, a primary throttle, a supplemental air inlet for the primary mixing chamber adapted to be controlled by the primary throttle throughout its operating range, a secondary air passage supplying air to the secondary mixing chamber, a valve in said secondary air passage operable by the throttle valve only after a predetermined opening movement of the latter, and a suction operated valve in said secondary air passage operable only after said last named valve is open.

41. A charge forming device for a multicylinder internal combustion engine comprising a plurality of primary mixing chambers, fuel and air inlets therefor, a throttle controlling the flow of mixture from all of said chambers, a plurality of secondary mixing chambers each of which is adapted to receive a primary mixture of fuel and air from one of said primary mixing chambers, a plurality of supplemental air passages, one for each primary mixing chamber and all of which are adapted to be regulated by the throttle, a single secondary air passage supplying air to all the secondary mixing chambers, a manually operated valve in said secondary air passage and a suction operated valve in said air passage.

42. A charge forming device for a multicylinder internal combustion engine comprising a plurality of primary mixing chambers, fuel and air inlets therefor, a throttle controlling the flow of mixture from all of said chambers, a plurality of secondary mixing chambers each of which is adapted to receive a primary mixture of fuel and air from one of said primary mixing chambers, a plurality of supplemental air passages, one for each primary mixing chamber, said supplemental air passages being regulable by the throttle throughout itsrange of movement, a single secondary air passage supplying air to all the secondary mixing chambers, a valve in said secondary air passage adapted to be operated by the 1 throttle only after a predetermined opening movement thereof, and a suction operated valve in said secondary air passage operable only after said last named valve is open.

43. A charge forming device for a multicylinder internal combustion engine comprising a plurality of primary mixing chambers, fuel and air inlets therefor, a throttle controlling the flow of mixture from all of said chambers, a plurality of secondary mixing chambers each of which is adapted to receive a primary mixture of fuel and air from one of said primary mixing chambers, a plurality of supplemental air passages adjacent the throttle one for each primary mixing chamber so positioned that all of said passages are controlled by the throttle, a single secondary air passage supplying air to all of said secondary mixing chambers, a valve in said last named passage operated by the throttle and a suction operated valve therein.

44. A charge forming device for internal combustion engines comprising a primary mixing chamber, a secondary mixing chamber adapted to receive a primary mixture of fuel and air from said primary mixing chamber, a throttle controlling the flow of primary mixture, a main air inlet chamber, a main air passage connecting the primary mixing chamberwith said air inlet chamber, a'supplemental air passage also connecting the main air chamber and primary mixing chamber and controlled by the throttle, a secondary air passage connecting the main air inlet chamber with the secondary mixing chamber, and suction and manually operated valves in said secondary air passage.

45. A charge forming device for internal combustion engines comprising a primary mixing chamber, a secondary mixing chamber adapted to receive a primary mixture of fuel and air from said primary mixing chamber, a throttle controlling the flow of primary mixture, a main air inlet chamber, a main air passage connecting the primary mixing chamber with said airinlet chamber, a supplemental air passage also connecting the main air chamber and primary mixing chamber and controlled by the throttle, a secondary air passage connecting the main air inlet chamber with the secondary mixing chamber, a throttle operated valve in said secondary air passage and a suction operated valve in said secondary air passage operable only after the throttle operated valve is opened.

46. A charge forming device for internal combustion engines comprising a primary mixing chamber, a secondary mixing chamber adapted to receive a primary mixture of fuel and air from said primary mixing chamber, a throttle controlling the flow of primary mixture, a main air inlet chamber, a main air passage connecting the primary mixing chamber with said air inlet chamber, a supplemental air passage also connecting the main air chamber and primary mixing chamber and controlled by the throttle throughout its operating range of movement, a secondary air passage connecting the main air inlet chamber and the secondary mixing chamber, a valve in said secondary air passage operable only after the throttle has-made a predetermined movement, and another valve in said passage operable only after the opening movement of said last named valve has begun.

47. A charge forming device for internal combustion engines comprising a secondary mixing chamber, means for supplying air to said secondary mixing chamber, a primary mixture passage delivering a primary fuel mixture to said secondary mixing chamber, a primary throttle for regulating the eifective area of the primary mixture passage, means for supplying fuel and air to said primary mixture passage, and another fuel supply -means for temporarily supplying additional fuel to the primary mixture passage on opening movements of the primary throttle to enrich the mixture during the acceleration period.

48. A charge forming device for internal combustion engine comprising a secondary mixing chamber, means for supplying air to said secondary mixing chamber, a primary mixture passage delivering a primary fuel mixture to said secondary mixing chamber, a primary throttle for regulating the effective area of the primary mixture passage, means for supplying fuel and air to said primary mixture passage, a main air valve controlling the admission of air to the mixture passage, another fuel supply means for temporarily supplying additional fuel to the primary mixture passage to enrich the mixture during the acceleration period, and means operated by the air valve for rendering said fuel supply means effective as said primary throttle is opened.

49. A charge forming device for internal combustion engines having, in combination, a plurality of primary carburetors adapted to supply a primary fuel mixture to a plurality of secondary mixing chambers, means for admitting fuel and air to the primary carburetors, and a single means for supplying additional fuel to all of said primary carburetors during the acceleration period.

50. A charge forming device for internal combustion engines comprising a secondary mixing chamber, located adJacent the engine intake port, means for supplying air to said secondary mixing chamber, a primary mixture conduit adapted to deliver a primary fuel mixture to said secondary mixing chamber, a primary throttle in said mixture passage for controlling the flow therethrough, means for supplying fuel and air to said primary mixture passage, and another fuel supply means for temporarily supplying additional fuel to the primary mixture passage on opening movements of the primary throttle to enrich the mixture during the acceleration period.

51. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixture passage adapted to supply a primary fuel mixture to said secondary mixing chamber, means for supplying air to said secondary mixing chamber, means for supplying air and fuel to said primary mixture passage at a point relatively remote from the secondary mixing chamber, and another fuel supply means for temporarily supplying additional fuel to the primary mixture passage on opening movements of the primary throttle, to enrich the mixture during the acceleration period.

52. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixture passage adapted to supply a primary fuel mixture to the secondary mixing chamber, a secondary air passage for 1 supplying air to said secondary mixing chamber, means for supplying air and fuel to said primary mixture passage, said primary mixture passage and said primary air passage being of substantially the same length and another fuel 1 supply means for temporarily supplying additional fuel to the primary mixture passage on opening movements of the primary throttle to enrich the mixture during the acceleration period. 1

53. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixture passage adapted to supply a primary fuel mixture to the secondary mixing chamber, a secondary air passage for 1 supplying air to said secondary mixing chamber, a fuel inlet for supplying fuel to the primary mixture passage, a single air inlet admitting air to both said secondary air passage and said primary mixture passage, and another fuel supply means for temporarily supplying additional fuel to the primary mixture passage on opening movements of the primary throttle to enrich the mixture during the acceleration period.

54. A charge forming device for internal comsecondary mixing chambers, one of said primary mixture passages being associated with each of said secondary mixing chambers, means for supplying fuel and air to all of said primary mixture passages, a single secondary air passage for supplying air to all of' said secondary mixing chambers and a single fuel supply means for supplying additional fuel to all of said primary mixture passages.

55. A charge forming device for internal combustion engines having, in combination, a plurality of secondary mixing chambers, a plurality of primary mixture passages for supplying a primary mixture of fuel and air to said secondary mixing chambers, one of said primary mixture passages being associated with each of FRED E. ASELTINE. CARL H. KINDL. WILFORD H. TEETER. 

